.modalbox{
    position: absolute;
    left: 0;
    top: 0;
    z-index: 1;
    background: rgba(0, 0, 0, 0.5);
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
}
.box{
    width: 400px;
    height: 400px;
    background: white;
    border-radius: 5px;
    box-shadow: 0 0 3px 3px gray;
}